The speed of the boat in still water is 15 km/hr.It can go 45 km upstream and return downstream to original point in 6 hours and 45 minutes.

Question

The speed of the boat in still water is 15 km/hr.It can go 45 km upstream and return downstream to original point in 6 hours and 45 minutes.Find tge speed of the stream​

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Parker 3 weeks 2021-10-07T13:40:27+00:00 2 Answers 0 views 0

Answers ( )

    0
    2021-10-07T13:42:06+00:00

    Answer:

    ANSWER

    Given :

    Speed of boat in still water =15 km/hr

    Let x be speed of the stream in km/hr

    Speed of the boat upstream =15−x

    Speed of the boat down stream =15+x

    Time taken for upstream T

    1

    =

    15−x

    30

    Time taken for downstream T

    2

    =

    15+x

    30

    Given, T

    1

    +T

    2

    =

    2

    9

    =

    15−x

    30

    +

    15+x

    30

    =

    2

    9

    =30(

    15−x

    1

    +

    15+x

    1

    )=

    2

    9

    =30(

    (15−x)(15+x)

    15+x÷15−x

    )=

    2

    9

    =

    225−x

    2

    30×30

    =

    2

    9

    =

    225−x

    2

    100

    =

    2

    1

    ⇒225−x

    2

    =200

    ⇒x

    2

    =25

    ⇒x=5 ….(∵x is +ve)

    ⇒x=5 km/hr

    Speed of the stream =5 km/hr.

    0
    2021-10-07T13:42:22+00:00

    Answer:

    Speed of stream = 15 km/hr. Hence upstream speed = 60 – 15 = 45 km/hr. So time taken to cover 20 km = 20/45*60 = 26.67min.

    Step-by-step explanation:

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